Conventionally, a so-called ejector type bubble generator has been used as an apparatus for disperse-mixing a great amount of a gas with a liquid. With this bubble generator, a liquid jet sprayed out from a nozzle hole or nozzle holes is made to pass through a gas to be mixed with the liquid, and the gas around the liquid jet is drawn in it. Then, the gas mixture is jetted out into tile liquid From a throttle or throttles having substantially the same diameter as that of the nozzle hole or tile nozzle holes and provided coaxially therewith. In this way, a liquid is mixed with fine bubbles.
In some apparatuses, the fine bubble-dispersed jet produced by the above-mentioned processes is supplied to the lower portion of a tank in which the bubbles are dispersed as they are rising. A great amount of gas is dissolved in the liquid while the fine bubbles are rising in the liquid in the tank, thereby producing a Liquid into which a required gas is dissolved.
In some other apparatuses, a liquid and a gas are supplied to a pressure pump and are pressurized to dissolve the gas into the liquid. Thereafter, the pressure on tile gas-dissolved liquid is reduced so as to precipitate the gas dissolved in the liquid, thereby forming bubbles in the liquid.
When the conventional ejector type bubble generator is used, the liquid jet nozzle holes and throttles must be aligned with each other, leading to a complicated structure of the apparatus and requiring difficult assembling processes. The liquid-dissolving apparatus using a bubble tank requires a long starting time for obtaining a liquid into which a gas begins to be fully dissolved and provides poor manufacturing efficiency.
In the conventional apparatus using a pressure pump, a gas and a liquid are supplied together to the pressure pump. This is likely to produce cavitation in tile pressure pump. In order to prevent the cavitation, the material and the structure of the pressure pump are limited. Upon producing bubbles under the pressure dissolving process, only a gas dissolved in the liquid under pressure is precipitated, and thus it is impossible with the pressure reducing process to precipitate a larger amount of gas than that dissolved in the liquid. Accordingly, a very high pressure is required in order to produce a great amount of bubbles. This makes the apparatus bulky and cavitation is general very easily.
This invention has been made in order to overcome the problems which the prier art encounters and is intended to provide a method and an apparatus for dissolving a gas into and mixing the same with a liquid, which has a simple structure, forms fine bubbles in the liquid continuously and efficiently and mixes a great amount of gas with a liquid and dissolves the gas into the liquid efficiently.